Human-powered vehicles are used as a popular method of transport and exercise. Bicycles and handcycles are examples of human-powered vehicles used by people of many different abilities. A bicycle has two wheels and is powered by a person's legs, whereas a handcycle typically has three wheels and is powered by a person's arms. A handcycle, also called a handbike or hand trike, is propelled and steered through manipulation of the handlebars. The handlebars of a handcycle are coupled to one or more gears which turn a drive wheel or wheels on the handcycle. A rider rotates the handlebars in a crank-like motion to power the handcycle. A rider may operate a handcycle while sitting or reclining in a seat of the handcycle. A rider's legs may rest in stirrups or be secured to the frame of the handcycle. Because handcycles do not require use of the rider's legs, many riders with disabilities can use handcycles.
Handcycles are often designed with one front wheel and two back wheels but may also be designed in other configurations, such as with one back wheel and two front wheels. One common steering mechanism for the handcycle with a single front wheel is called fork-steering. Fork-steering requires the front wheel to turn or tilt with respect to the back wheels. In a fork-steering design, the handcycle frame has two portions. A front frame portion, called the fork, provides a mounting point for the handlebars and front wheel. A main frame of the handcycle provides a mounting point for the seat and back wheels. The fork moves freely with respect to the main frame so that the front wheel can be aimed in a direction different from the back wheels. Aiming the front wheel allows the rider to steer the handcycle. A rider manipulates the handlebars to turn or tilt the fork in order to steer the front wheel of the handcycle.
Many people who require a wheelchair for daily transportation can operate a handcycle. A person who uses a wheelchair must maneuver off of the wheelchair or other seat or device and onto the handcycle. When transferring from a wheelchair onto a handcycle, a rider grasps various parts of the handcycle for balance or stabilization. For example, a rider holds onto a handlebar or frame portion of the handcycle as the rider pulls the rider's body onto the handcycle. As another example, a rider leans onto a seat or frame portion of the handcycle for balance as the rider shifts body weight onto the handcycle.
During transition onto or off of the handcycle, the steering mechanism which allows the front fork of the handcycle frame to move freely with respect to the rest of the handcycle frame also makes the handcycle unsteady. For example, when the rider holds onto a handlebar while the rider shifts weight onto the handcycle, the rider pulls or pushes on the handlebar and the handlebar movement causes a wheel to turn or tilt. The unsteadiness of a handcycle due to the handcycle's moving parts can make maneuvering onto or off of the handcycle difficult, unsafe, or dangerous for a rider depending on the rider's physical capabilities. An unexpected turn or tilt of a wheel or frame during transfer onto or off of the handcycle can cause the rider to lose balance. A rider's loss of balance due to the handcycle's unsteadiness can cause injury if a rider falls or if rider's limbs are caught or tangled in the handcycle components.
To reduce the risk of injury and to make transfer onto and off of the handcycle easier, some riders use the assistance of another person. An assistant holds the handcycle to reduce movement of the handcycle and to help prevent one portion of the frame from turning, tilting, or rotating with respect to the other portion. The assistant thereby keeps the handcycle steady while the rider positions onto the handcycle. A handcycle rider who requires assistance with steadying the handcycle has limited independence in the use of a handcycle, because the rider cannot safely or easily get onto or off of the handcycle if the rider is alone.